Sea star wasting disease is severely impacting some species in the Salish Sea, especially the sunflower sea star, Pycnopodia helianthoides, a new study has found.
According to a study by researchers at UC Davis School of Veterinary Medicine’s SeaDoc Society and Cornell University, the sea star wasting disease, which broke out in 2013 is responsible for massive death of several species of sea stars. Infected animals develop lesions that eat away tissue, with limbs dropping off as the animals die. The disease has been linked to a virus, although environmental factors may also be involved.
Researchers are of the opinion that because sunflower stars are major predators, decline in their population will probably change the ecosystem. The Salish Sea, which straddles the U.S./Canadian border and includes Puget Sound and the waters east of Vancouver Island, is home to a diverse population of sea stars. The animals are important predators, eating urchins and other animals.
One of the reasons why researchers picked Salish Sea for their study is the diversity of sea star and it being one of the best places where impact of wasting disease on different species can be studied.
The researchers used a combination of data collected by scientific divers during 2014-15 and long-term data collected by trained recreational scuba divers through the Reef Environmental Education Foundation, or REEF.
“The REEF data were amazing. We were able to compare eight years of pre-epidemic data to the outbreak to show how devastating declines were for the sunflower stars,” said Diego Montecino-Latorre, UC Davis graduate student, veterinarian and lead author on the study.
Sunflower sea stars hit hard
The results showed some species were hit hard, while others actually increased in number. Populations of sunflower sea stars dropped dramatically after the beginning of the epidemic, and several other sea star species, including the spiny pink star, Pisaster brevispinus, also declined. Numbers of the less-common leather star (Dermasterias imbricata) and two species of sea urchin, which are prey for sea stars, increased after 2013.
The virus outbreak continues, and will have lasting effects on the ecosystem. Sunflower sea stars have effectively disappeared from the Salish Sea, the study concludes. Likely as a result, numbers of urchins have increased, which in turn will lead to more grazing on kelp. Researchers say that they are in discussions with the National Marine Fisheries Service to get the sunflower sea star listed as a “species of concern.”
“This study revealed the need to generate a plan supporting the persistence of what used to be the most common sea star species in the Salish Sea,” said Montecino-Latorre.
The findings are published in the journal PLOS One.